Earlier this week, the EML came on; fault code was P0341 - camshaft position sensor. Car was running OK, so I cleared the code to see if it returned - which it did.

I continued to use the car, but ordered a replacement camshaft sensor. In the interim, I noticed that when first turning on the ignition, "Parking Brake" would occasionally flash up, along with "Electronic Immobiliser Fault". The car would turn over, but not fire. Switching off and on again fixed it.

This morning (Saturday), I picked up the new sensor, fitted it, cleared all the fault codes, and for good measure, carried out the battery disconnect procedure to reset the BSi.

First trip out, it was fine; 2nd trip out (was at Tesco), EML light came on, along with the "Parking Brake" message and the "Electronic Immobilser Fault" message. I switched off, switched on and it was fine, although the EML light remained on.

When I got home, I checked the fault code, and got two different ones: P0135 and P0138 (from memory) - indicating oxygen sensors. Something was clearly amiss, so I decided to check the BSi connections (following the battery disconnect procedure).

Despite the little waterproof jacket around the connectors, water had got in to one of them (one nearest the front of the engine) - blue gunk and corrosion on the pins and in the plug. I removed the BSi, cleaned it up as best I could, and replaced it. Now it won't start at all - "Parking Brake" and "Engine Immobiliser Fault". Turns over, but doesn't fire.

The ECU is currently sitting indoors, close to a radiator, where I'm hoping it will dry out. I'll have a look at the plug later as well.

Worse case scenario is a new BSi - well, not a new one, but a used one. Car is 10 years old and not worth much, and I know replacement BSi units from Citroen are hundreds.

The basic searching I have done (eBay) indicates BSi units are readily available, although I assume I'll have to make sure it's compatible with my model. The other assumption I have is that it won't be a straight-swap - Citroen will have to re-programme it.

Anything else I need to think about? I've looked on the FAQs, and you can't search for BSi on the forum search because it's < 4 characters

Leaving it overnight made no difference - and as I discovered this morning, it was never going to. What I had previously assumed were 'blank pins' in the BSi side connector were in fact completely corroded pins. So it looks like it'll be off to a repair outfit after all.

Sorry to hear of your problems with ECU. I too had a similar thing, but the garage I used repaired the corroded pins for me. A place that repairs units is ECU Technologies (got them from Google ), may be helpful to ring them. Seems this water ingress is quite common, I have now made another "boot cover" over the original one, working well at the moment with all this rain down here in the SW.

Chap who does my MoT tests recommended BBA-Reman - so the ECU has gone up to them this morning - one of the reasons I chose them was that they are fairly local (Kent) and I've seen some positive reviews, and there was a write-up on Honest John. Turn-around time is 5-10 days. Will post when I have news.

Yes the BSI seems prone to water damage, but have you seen all the reports on TV about the floods and seen the fools who drive through them in their cars at speeds that would be banned on Lake Windermere. Their bow waves make the QE2 look positively mundane. Wait a few months and there will be many more laid up cars with corroded circuits.

Update: I hadn't heard anything from BBA Reman, so I called them, and was advised that it would probably be next week before they could tell me anything. To be fair, they did say 5-10 working days and they received it last Tuesday. Fortunately, I'm managing without the Pic at the moment. For anyone else going this route - BBA don't look as fast as others claim to be.

On a related note - the terms "BSi" and "ECU" appear to be used interchangeably - incorrectly. I've done this myself - correct title of this thread should be "ECU woes".

If you are unable to have yours repaired the cheapest thing to do is replace the ECU and bsi, on ebay they are often sold together, I had the same problem brought the ecu and bsi to match my engine size and swapped them over. No need to have them reprogrammed if you get the two together, cost me £80 instead of £600 job done.

Well - my ECU cannot be repaired, so I'll be going the 2nd hand ECU & BSi route. Research I have done so far (and help on this thread) indicates that I need a matching ECU, BSi and key transponder. There seem to be a few of these 'kits' on eBay right now.

My question is whether the ECU/BSi/transponder has to fit my model year. I have a 2004 facelift model - all of the ECU/BSi bundles I've seen for 1.8 petrol engined Pics on eBay seem to be for 1999-2004 models, as opposed to the 2004-2009 models. The Sagem ECU model number is different, but as the engine is the same, I'm wondering whether it makes any difference? I'm assuming the physical connections are the same.

as long as the engine size is the same then it can be from any 1999-2009 Xsara Picasso. I have a 2001 car but I put one on from a 2005 car. The only thing that will be different is the mileage, when you change the ecu and bsi over it will display the mileage from that car.

Thanks for the advice. I'm aware of the potential mileage change issue and I'm not too concerned about that - took pictures of the reading before taking the ECU out, and the car is not worth much anyway.

I am hearing different things about compatibility though - a breaker I spoke to this morning said I should replace my ECU with one of the same model number. I also rang the dealer - more for a giggle about the price than anything - he gave the same advice.

mark23: you went from an older version to a newer version - and that clearly works for you. Will it work fine going from a newer version to an older one? Has anyone else done that on the 1.8 petrol? I'm asking this question because I've not seen any with my model number available: S2PM-270. They all seem to be S2000-1

I've bitten the bullet and sourced an earlier ECU/BSi/transponder kit from eBay. It was £40 - in car terms, I still count this as cheap, so I'm happy to take the risk that an earlier ECU/BSi is not forwards compatible with my 2004 facelift car (I know from mark23's post that the ECU/BSi is backwards compatible with earlier cars). The ECU model number is different, which is my concern, but the worst thing that can happen is that it doesn't work and I have to sell the ECU on.

I'll probably be banned from the forum for blasphemy, but I've currently got a VW Jetta Blue Motion as a hire car for a business trip (currently in Stockton-on-Tees - Sir Lancelot territory?). It's phenomenal. Trip computer is reading 70mpg. Even allowing for a 10% over-read, that's excellent at motorways speeds. As I charge my clients mileage, then I will still make money after the cost of car hire and fuel is taken in to account.

The £40 kit never turned up - apparently it got damaged and was returned to the sender by TNT.

I ordered another one from a different eBay seller - this one was from a 2000 X reg. I can confirm that the BSi is completely different - size and connectors. The ECU looks the same but has a different model number.

I am in touch with the supplier of the second one to see if he has the kit I need. General web searching indicates that 'broken' 1.8 Mk2 Pics are less common than the other models - plenty of 1.6 models out there!

Since my last post, I used a couple of federated sites to try and source the right ECU kit for my Pic. That was not successful, but another ECU repair outfit got in touch as a result of that federated request. They advised they would assess my unit and if it couldn't be repaired, they wouldn't charge me - I'd only pay out postage. They also advised they had managed to fix units that BBA Reman had said couldn't be fixed. That's the route I went; they said they could fix it - ECU arrived back yesterday, and car started first time (I did charge the battery as it's the original battery - 10 years old - and car had been sitting for > 6 weeks)

The company was Autotek in Bournemouth: http://autotekelectronics.com/ - the cost was £232.24. Allowing for postage, the failed BBA Reman route, and the purchase of the wrong kit from eBay (returned and refunded except for postage), it's cost £300 to fix. Ironically, there is a suitable kit on eBay now - £125. Also - wife was in post office the other day, and someone else was posting off a water damaged Picasso ECU.

Only two problems now:

1. Rear wiper no longer parks correctly (actually parks quite randomly) and exhibits odd behaviour - it started wiping when I unlocked the car, and when I was reversing.

2. Radio does not work. There's power to it, because it whirrs when you press the CD eject button.

I'll post separately on the above.

I would not recommend BBA Reman - they took 10 days to tell my ECU could not be repaired; Autotek told me the same day they got it that it could be repaired, and I got it back within 10 working days of sending it.